1. FIGURE 4.4 The water vapor content (humidity) inside this air parcel can be expressed in a number of ways.
Fig. 4-4, p.80

2. H2O
other gases O2 N2

3. FIGURE 4.5 Saturation vapor pressure increases with increasing temperature. At a temperature of 10°C, the saturation vapor pressure is about 12 mb, whereas at 30°C it is about 42 mb. The insert illustrates that the saturation vapor pressure over water is greater than the saturation vapor pressure over ice.
Fig. 4-5, p.81

4. Temperature decreases Sat. vap. press. decreases RH increases
FIGURE 4.6 When the air is cool (morning), the relative humidity is high. When the air is warm (afternoon), the relative humidity is low. These conditions exist in clear weather when the air is calm or of constant wind speed.
Temperature decreases
Sat. vap. press. decreases
RH increases
Fig. 4-6, p.82
Fig. 4-5, p.81

5. Temperature increases Sat. vap. press. increases RH decreases
FIGURE 4.6 When the air is cool (morning), the relative humidity is high. When the air is warm (afternoon), the relative humidity is low. These conditions exist in clear weather when the air is calm or of constant wind speed.
Temperature increases
Sat. vap. press. increases
RH decreases
Fig. 4-6, p.82
Fig. 4-5, p.81